I have follwed to the letter the instructions in the article, but when I try to open the "crontab" file, as instructed, I get the following message:

dyld: pico Undefined symbols:
pico undefined reference to _AL expected to be defined in /usr/lib/libSystem.B.dylib
pico undefined reference to _CE expected to be defined in /usr/lib/libSystem.B.dylib
pico undefined reference to _CL expected to be defined in /usr/lib/libSystem.B.dylib
pico undefined reference to _CM expected to be defined in /usr/lib/libSystem.B.dylib
pico undefined reference to _CS expected to be defined in /usr/lib/libSystem.B.dylib
pico undefined reference to _DC expected to be defined in /usr/lib/libSystem.B.dylib
pico undefined reference to _DL expected to be defined in /usr/lib/libSystem.B.dylib
pico undefined reference to _DM expected to be defined in /usr/lib/libSystem.B.dylib
pico undefined reference to _ED expected to be defined in /usr/lib/libSystem.B.dylib
pico undefined reference to _EI expected to be defined in /usr/lib/libSystem.B.dylib
pico undefined reference to _IC expected to be defined in /usr/lib/libSystem.B.dylib
pico undefined reference to _IM exTrace/BPT trap